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Subject: Re: DB NPS (anyone know the position used)?

Author: leonid

Date: 15:31:21 01/26/00

Go up one level in this thread

On January 26, 2000 at 13:24:21, Ed Schröder wrote:

>>Posted by Peter W. Gillgasch on January 26, 2000 at 09:18:55:
>>In Reply to: Re: DB NPS (anyone know the position used)? posted by Ed
>>Schröder on January 26, 2000 at 03:07:42:
>>On January 26, 2000 at 03:07:42, Ed Schröder wrote:
>>>On January 25, 2000 at 23:57:33, Ernst A. Heinz wrote:
>>>>> In a one by one setting it does not matter at all.
>>>>Still not convinced: a quiescence node that produces a direct
>>>>"stand pat" cutoff obviously generates less work than one
>>>>which fails to do so -- even in hardware!  *** QED ***
>>>>Or am I missing something?
>>>Something else... I always wondered about this free 4-ply evaluation. I
>>>can understand that evaluation for the current position done in hardware
>>>is possible in a few cycles. I can't understand this also to be true for
>>>4 plies as it should involve: search, hash table, q-search etc. In other
>>>words a complete chess program.
>>Well of course they have a complete chess program for interior nodes
>>in hardware as you know. The idea why I think that the position does
>>probably not matter too much is because something like 0.07 percent
>>of the nodes they do are calculated on the SP and the remaining
>>99.93 percent of the nodes are done on the hardware where the transition
>>from father to sibling and back has a fixed cost regardless of move
>>ordering. I am not saying that the size of the tree is not influenced
>>by the position, I am also not saying that the time it takes to complete
>>a 4 ply search on the chips does not depend on the position.
>>You have experience with one by one move generators since your ARM
>>program did that. What is your gut feeling, assuming that all moves
>>spend the same time in MakeMove/UnmakeMove (hypothetical) and all
>>your move  generators need the same time to produce the next move
>>(only a little hypothetical) and you have no instruction count
>>differences between the usual case versus the "get out of check" case,
>>would you see any major NPS differences between different positions ?
>I think you mixed me up with somebody else. I always do and have done
>a full move generation and then sort the move list first based on a fast
>static evaluation. I have tried the one by one approach but it was not

I am curious to see if I understood correctly what you have said. You find for
each ply all the moves and aline them in the way that the most promissing goes
first. What I would like to know is if all the moves that you generate for the
ply are legal.

In my logic I use almost everywhere legal moves and I find all the moves for the
each ply before using them. Found that very few do the same. Now I see that
probably you do the same. This is why I make this question.


>I suspect the reason is Rebel's expensive evaluation function. If you have
>a fast eval NPS will drop considerable doing a full move generation plus a
>quick-sort. Having a slow eval like Rebel you hardly see the NPS drop and
>you can afford such time consuming things.
>>For me it is pretty much constant, ups and downs by maybe 1/6 which
>>I attribute to the varying execution times of MakeMove/UnmakeMove and
>>the differences between "in check" and "not in check" nodes.
>>-- Peter

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